There is no constraint on layer naming. However, as you import your PSD into Modeler, the names of your layers will become names of your drawing objects. It is suggested to keep the name simple and literal. (Image below shows the resulted "Parts" name inherited from the imported PSD)

Cleaning up the canvas

For the best result, make sure that there is no tiny pixels of paint that is almost invisible.

Modeler will pick up those unneeded pixels upon importing the PSD, and thus allocate meaningless polygons to those pieces and corrupting the quality of your texture.

As a prevention, utilize the lasso tool to round up and delete possible pixels in open areas.